Amino acid accumulation by the corneal epithelium accounts for 95% of total amino acid accumulation by the intact cornea. Examination of Na ion plus K ion - ATPase activity, hexonse monophosphate shunt activity and metabolite levels in Bufo marinus corneal epithelial cells will be carried out in order to elucidate the roles of various metabolic processes in control of amino acid transport. Compounds studied for their effects on both the sodium-dependent A-transport system and the sodium-independent L-transport system include lactate, ascorbate, glutathione, NADP ion and NADPH. The effects of he glutathione oxidizing agents diamide and t-butyl hydroperoxide will also be examined as well as sulfhydryl reagents such as N-ethyl meleimide, P-hyroxy mercuribenzoate and sodium tetrathionate. The role of reducing agents in these transport processes will also be examined.